Re: Spirit 2.1 - Question about rules and phoenix

> I am rewriting a parser for algebraic expression from the old spirit
> classic to spirit QI.

<snip />

> However I need to split the rule Expression to insert other parts. Doing
> this in the following way my code is no more working (it compiles but the
> result is wrong):
>
> template <typename iterator>
> struct SpiritCalculator : qi::grammar< iterator, std::vector<Real>(),
> ascii::space_type >
> {
>     SpiritCalculator() :
>         SpiritCalculator::base_type(Start)
>
>          Start =
>             (
>                 Expression % ','
>             )
>         ;
>
>         Expression =
>             (
>                 Element[qi::_val = qi::_1] >> *( PlusMinus[qi::_val =
> qi::_1] )
>             )
>         ;
>
>         PlusMinus =
>             (
>                 ( qi::lit('+') >> Element[qi::_val += qi::_1] ) |
>                 ( qi::lit('-') >> Element[qi::_val -= qi::_1] )
>             )
>         ;
>         Element =
>             (
>                   qi::double_
>             )
>         ;
>
>     qi::rule< iterator, Results_Type(), ascii::space_type > Start;
>     qi::rule< iterator, double(), ascii::space_type > Expression,
> PlusMinus, Element;
> }
>
> The two codes should do the same thing. However if I pass a string
> "2+4,1+2+3" to the first one he correctly return ( 6, 6 ) while the second
> one return ( 4, 3 ), which are the last two elements.
>
> Can anyone tell me how to make the second one working. I need that kind of
> structure to build my parser (I need to have PlusMinus, MultiplyDivide, and
> other operators spitted from the Expression).

Did you have a look at boost/libs/spirit/example/qi/calc3.cpp ? 

If you really want to split the rules as shown above, you'd have pass
the current value of Expression to PlusMinus. See attached.

HTH,
Chris

------------------------------------------------------------------------------
SOLARIS 10 is the OS for Data Centers - provides features such as DTrace,
Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW
http://p.sf.net/sfu/solaris-dev2dev

_______________________________________________
Spirit-general mailing list
Spirit-general <at> lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/spirit-general